Wireless telegraphy.



No. 786,132. PATENTED MAR. 28, 1905'. G. MARGONI. WIRELESS TELEGRAPHY;

APPLICATION FILED OUT. 13. 1903.

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UNITED STATES Patented March 128, 1905.

PATENT OFFICE.

GUGLIELMO MAROONI, OF LONDON, ENGLAND, ASSIGNOR TO MAR CONIS l/VIRELESSTELEGRAPH COMPANY, LIMITED, A CORPORATION OF GREAT BRITAIN.

WIRELESS TELEGRAPHY.

SPECIFICATION forming part of Letters Patent No. 786,132, dated March28, 1905.

Application filed October 13, 1903. Serial No. 176,844.

To all whom, it may concern:

Be it known that I, GUeLIELMo MARooNI, a subject of the King of Italy,residing in the city of London, England, (and having a postofficeaddress at 18 Finch Lane, in the said city of London,) have inventedcertain new and useful Improvements in Wireless Telegraphy, of which thefollowing is a full and true description, reference being had to theaccompanying drawings, which show diagrammatically three embodiments ofmy invention.

My invention relates to improvements in telegraphy through the naturalmedia by means of electric waves, and especially to circuits formingpart of a receiver by which tuned or syntonic effects can be obtainedand the effects of natural disturbances, such as thunderstorms, upon thereceiver are minimized.

According to my present invention an exposed aerial or elevatedconductor is grounded by means of several connections of differentinductance and capacity instead of by one, as has heretofore been theusual practice.

Referring to the accompanying diagrammatic drawings, Figure 1 shows oneform of apparatus useful in carrying out my invention. Fig. 2 shows asecond form of apparatus, and Fig. 3 shows a third form.

The most simple form of my invention is shown in Fig. 1, in which Arepresents the receiving-aerial adjustably connected to theinductance-coil Z; O, a condenser connected to the inductance-coil; R, asuitable receiver or detectorsuch as the magnetic detector of myinventions described in a paper read by me before the Royal Society ofLondon, on June 12, 1902, and which are described in Electrical Worldand Elma near, published at New York city, July 5 and 12, 1902, and alsodescribed and claimed in an application, Serial No. 132,974, filedNovember 28, 1902, for Letters Patent of the United Statesconnect ed tothe condenser.

One terminal, 9, of the detector is grounded at G, and another groundconnection, E, which is preferably flexible or adjustable, is joined tothe inductance Z at a certain point, the position of which is dependentupon the period of the electric wave radiated from the distanttransmitting-station. This receiving system is syntonized or attuned toone particular frequency of electrical waves radiated from any one of anumber of differently-attuned distant electric radiators in thefollowing manner:

The size of the condenser O is fixed, and the I inductance Z is variedby adjusting its connection with the aerial until signals are receivedon the responder or detector R. Then by sliding the flexible oradjustable ground connectionE along the inductance Z or otherwise apoint is found at which, if a new ground connection is established,waves of the particular frequency radiated from a given distanttransmitting-station from which it is desired to receive signals will bereceived and detected to the exclusion of signals transmitted from otherstations radiating waves of different frequencies. I have discoveredthat this ground connection E may be made without weakening but ratherstrengthening the signals in the detector R.

The position of the ground connection E in the inductance Z is dependentupon the length of the Wave to be detected. It should be connected at ornear the node or point of nopotential of the electric wave which it isdesired to read or detect, and the detector R will then be unresponsiveto electrical waves of frequencies other than that for which the systemhas been adjusted as described.

By means of this present invention a very sharp selectivity of signalsis obtained and the troublesome effects of atmospheric electricity arelargely or wholly eliminated.

In Fig. 2 is shown a modification of Fig. 1, lhe ground connection E ofFig. 1 being replaced by another at E of Fig. 2, the position of whichon the inductance Z being found similarly to the adjustment of E, ashereinbefore described.

Many extensions of the arrangements shown in Figs. 1 and 2 will readilysuggest themselves.

By reference to Figs. 1 and 2 it will be seen that the receivingapparatus therein illustrated each comprises two associated circuits,one (an open circuit) including the aerial A, the conductor E, (or E,)and that portion of the inductance-coil Z between the respective pointsof contact thereof with the aerial and the conductor and the secondcircuit (a closed circuit) including the responder or detector R,condenser C, conductor E, (or E, l and that portion of theinductance-coil between the condenser and the conductor E.

It is essential that a condenser shall be included in the so-calledclosed circuit; otherwise the apparatus will not properly operate,because if a condenser is omitted from said circuit that circuit cannotbe tuned to respond to the proper wave period.

As stated, the flexible or adjustable ground connection E may bevariably connected with or arranged to simultaneously include more orless of the turns of the inductance-coil in the twocircuits referred to.Now when the conductor E is adjusted to a certain position (forinstance, that shown in Fig. 1) and electromagnetic wavcs fall uponaerial A such waves will excite oscillations in the aerial, and if thetime period of the open-circuit aerial plus the included turns of theinductance-coil is the same as that of the condenser C plus the turns ofthe inductance-coil included in circuit with said condenser and if thisagrees with that of the waves incident the responder will be affected.11", however, waves of other period fall upon the aerial, there will belittle or no sympathetic vibration excited in the condenser-circuit, andthe responder will not be affected.

in Fig. 3 is shown one such extension, comprising a series of similarsyntonic circuits, each in tune with the wave transmitted, the systembeing grounded at the nodal points E, E, E E and G, which are determinedby the periodicity of the wave transmitted. This arrangement gives aparticularly sharp attunement and is especially adapted to eliminate thestray or extra signals caused by atmospheric disturbances.

While I have described and shown three embodiments of my invention, I donot desire to be understood as limiting my claims thereto. Obviouslyother modifications within the scope of my invention will readilysuggest themselves to persons skilled in wireless telegraphy.

WVhat I claim is 1. At a receiving-station employed in wirelesstelegraphy, the combination of an open circuit containing anoscillation-receiving conductor and inductance .in circuit therewith,and a closed oscillation-circuit containing inductance and a condenser,and an adjustable contact arranged to alter the inductance of the twocircuits, substantially as described.-

2. At a receiving-station employed in wireless telegraphy, thecombination of an open circuit containing anoscillation-receivingconductor and inductance in circuit therewith, incombination with a closed oscillation-circuit containing a condenser andincluding a contact for adjustably including the inductance in bothcircuits, substantially as described. 3. At a receiving-station employedin wireless telegraphy, the combination of an open circuit containing anoscillation-receiving conductor and inductance in circuit therewith, incombination with a closed oscillation-circuit containing inductance anda condenser, an adjustable contact arranged to alter the inductance ofthe two circuits, and a receiving-circuit magnetically connected withthe closed circuit, substantially as described.

4. At a receiving-station employed in wireless telegraphy, thecombination of a receiver or responder earthed at one end and joined atthe other end to a condenser and variable inductance in series, the freeend of said in-' ductance being earthed and also connected to anoscillation-receiving conductor having variable inductions in seriesWith it, substantially as described.

5. At a receiving-station employed in wireless telegraphy, thecombination of a receiver or responder earthed at one end and connectedwith a condenser and inductance joined in series, the free end of theinductance being earthed, and an oscillation-receiving conductor,adjustably connected with said inductance, substantially as described.

6. At a receiving-station employed in Wireless telegraphy, thecombination of an open oscillation-receiving circuitcontaininginductance, a closed oscillation-circuit containing inductanceand a condenser, and means for altering the inductance of both of saidcircuits without altering the sum of the inductance of the two circuits,substantially as described.

GUGLIELMO MARCONI.

Witnesses:

DELOS HOLDEN, WM. H. BERRIGAN.

